CircularLinkedList_Operations

#include<stdio.h>
#include<stdlib.h>

struct node
{
    int data;
    struct node *next;
};
struct node *start=NULL;

void create_List();
void display();
void insert_Begin(int value);
void insert_End(int value);
void insert_After(int number,int value);
void delete_Begin();
void delete_End();
void delete_After(int number);
void search(int value);

void create_List()
{
    int value;  
    struct node *new_node;
    struct node *current;
    printf("\n\nTo End : Enter -1\n\n");
	printf("Enter the Value : ");
	scanf("%d",&value);

	while(value!=-1)
	{
		new_node=(struct node *)malloc(sizeof(struct node*));
		new_node->data=value;
        if(start==NULL)
		{
            start=new_node;
			start->next=new_node;
        }
		else
		{   
            current=start;
            while (current->next != start)
	        {
	            current = current -> next;
	        }
	        current->next = new_node; 
	        new_node->next = start;
        }
        printf("Enter the Value : ");
	    scanf("%d",&value);
    }
}

void display()
{
	struct node *ptr;
    ptr=start;
    if(ptr==NULL)
    {
        printf("List is Empty.");
        return;
    }
    else
	{
        printf("The List is as follows \n");
    	do
	    {
		    printf("%d\t",ptr->data);
		    ptr=ptr->next;
	    }while(ptr!=start);
    }
    sleep(5); 
}

void insert_Begin(int value)
{
    struct node *new_node,*ptr;
    new_node = (struct node*) malloc(sizeof(struct node*));
    new_node->data = value;
    ptr=start;
    if(ptr == NULL) 
    {
        start = new_node;
        new_node->next = start;
        return;
    }
    while(ptr->next != start)
    {
        ptr = ptr->next;
    }
    new_node->next = start;
    ptr->next = new_node;
    start = new_node;
}

void insert_End(int value)
{
	struct node *ptr, *new_node;
	new_node=(struct node*)malloc(sizeof(struct node*));
	new_node->data=value;
    new_node->next=start;
	ptr=start;
	while(ptr->next!=start)
	{	
        ptr=ptr->next;
    }
	ptr->next=new_node;
}

void insert_After(int number, int value)
{
	struct node *ptr, *new_node, *preptr;
	ptr=start;
	new_node=(struct node*)malloc(sizeof(struct node*));
	new_node->data=value;
	ptr=start;
	while(preptr->data!=number)
	{
		preptr=ptr;
		ptr=ptr->next;
	}
	new_node->next=ptr;
	preptr->next=new_node;
}

void delete_Begin()
{
	struct node *ptr;
	ptr=start;
    if(ptr==NULL)
    {
        printf("The List is Empty, No Node to delete\n");
        return;
    }
    if(ptr->next == start)
    {
        start=NULL;
        free(ptr);
        return;
    }
    while(ptr->next!=start)
    {
        ptr = ptr->next;
    }
    ptr->next=start->next;
    free(start);
    start=ptr->next;    
}

void delete_End()
{
    struct node *ptr,*preptr;
    ptr=start;
    preptr=ptr;
    if(ptr==NULL)
    {
        printf("The List is Empty, No Node to delete\n");
        return;
    }
    if (start ->next == start)
    {
        free(start);
        start = NULL;
        return;
    }   
    while(ptr->next!=start)
    {
        preptr=ptr;
        ptr=ptr->next;
    }
    preptr->next=start;
    free(ptr);
}

void delete_After(int number)
{
    struct node *ptr,*preptr;
    ptr=start;
    preptr=ptr;
    if(ptr==NULL)
    {
        printf("The List is Empty, No Node to delete\n");
        return;
    }
    if(ptr == start && ptr == preptr->next)
    {
        printf("\nDeletion not possible.\n");
        return;
    }
    do
    {
        preptr=ptr;
        ptr=ptr->next;
    }while(preptr->data!=number && ptr!=start);
    preptr->next=ptr->next;
    free(ptr);
}

void search(int value)
{
    struct node *ptr;
    ptr=start;
    if (ptr == NULL)
    {
        printf("Element %d doesnt exist as List is Empty.\n",value);
        sleep(4);
        return;
    }
    int pos=1;
    while(ptr)
    {
        if(ptr->data==value)
        {
            printf("Element %d found at Position %d\n",value,pos);
            sleep(4);
            return;
        }
        if(ptr->next == start)
        {
        break;
        }
        ptr=ptr->next;
        pos=pos+1;
    }
    printf("Element %d doesn't exist\n.",value);
    sleep(4);
}

void main()
{
    int choice,val,num;
 
    while(1)
    {
        system("cls");
        printf("\nCircular LinkedList \n\n");
        printf("0. Create a List\n");
        printf("1. Insert Node at the beginning\n");
        printf("2. Insert Node at the End\n");
        printf("3. Insert Node after an entered value\n");
        printf("4. Delete Node from the beginning\n");
        printf("5. Delete Node from the end\n");
        printf("6. Delete Node after an entered value\n");
        printf("7. Search a value in the list\n");
        printf("8. Display the list\n");
        printf("9. Exit\n");
        printf("Enter Your Choice : ");
        scanf("%d",&choice);
        switch(choice)
        {
            case 0:
                create_List();
                break;
            case 1:
                printf("\nEnter the Value to be inserted at the Beginning : ");
                scanf("%d",&val);
                insert_Begin(val);
                break;
            case 2:
                printf("\nEnter the Value to be inserted at the End : ");
                scanf("%d",&val);
                insert_End(val);
                break;
            case 3:
                printf("\nEnter Value after which node will be Inserted : ");
                scanf("%d",&num);
                printf("\nEnter the Value to be inserted : ");
                scanf("%d",&val);
                insert_After(num,val);
                break;       
            case 4:
                delete_Begin();
                break;
            case 5:
                delete_End();
                break;
            case 6:
                printf("\nEnter the Value after which node has to be Deleted : ");
                scanf("%d",&num);
                delete_After(num);
                break;
            case 7:
                printf("\nEnter the Value to be Searched : ");
                scanf("%d",&val);
                search(val);
                break;
            case 8:
                display();
                break;
            case 9:
                exit(0);
                break;
            default:
                printf("\nInvalid Choice\n");
                break;
        }
    }
}